They're basically the same thing as Eggs, only with a Pokeball Base. Take a Pokemon and a Sprite of a regular Pokeball, choose one or two parts on the Pokemon, and Splice them onto a Pokeball. Then recolor the Pokeball the two main colors of the Pokemon you're using.
'Egging' does not really have a name that is widely recognized, but it is basically still Splicing, just with a different kind of Base Sprite than normal. If you want something along those lines to pass time, Pokemon-Balls go even quicker.
Er... An hour isn't a lot at Spriting. A lot of people take literally days to perfect a Sprite perfectly.
Also, just so you know, the Sprite isn't in the Color Limitations of D/P/Pt. I don't quite remember the amount of colors permitted to use on a Standard Pokemon Sprite, but I think it's somewhere around 16-20.
I'm rude with critiscism, just how I am. Look at someone named Yami Ryu and you'll see what 'rude' is. Anyway, I wasn't saying it looked stupid, it probably wouldn't look that bad if you had resized the limbs to match its body and not use inverted colors. It just looked sloppily put together.
Whoever suggested JPEG to you obviously was either being sarcastic or didn't know what they were talking about.
I apologize if I come off rude, that's just the way I am, and I can't help it.